Parametric study of various structural framing systems & effect of substructure modelling on super structure

PARAMETRIC STUDY OF VARIOUS STRUCTURAL FRAMING
SYSTEMS AND EFFECT OF SUBSTRUCTURE MODELLING ON
SUPERSTRUCTURE
A dissertation submitted to
The Maharaja Sayajirao University of Baroda
in partial fulfillment of the requirements for
the degree of
MASTER OF ENGINEERING (CIVIL)
in
STRUCTURAL ENGINEERING
bbyy
SSOOHHAAIILL SS.. DDHHAANNPPUURRWWAALLAA
UUnnddeerr tthhee GGuuiiddaannccee ooff
VVIISSHHAALL VV.. SSHHAAHH
DDeeppuuttyy MMaannaaggeerr
&&
DDrr.. GG.. SS.. DDOOIIPPHHOODDEE
AAssssoocciiaattee PPrrooffeessssoorr
AAPPPPLLIIEEDD MMEECCHHAANNIICCSS DDEEPPAARRTTMMEENNTT,,
FFAACCUULLTTYY OOFF TTEECCHHNNOOLLOOGGYY AANNDD EENNGGIINNEEEERRIINNGG,,
TTHHEE MMAAHHAARRAAJJAA SSAAYYAAJJIIRRAAOO UUNNIIVVEERRSSIITTYY OOFF BBAARROODDAA,,
VVAADDOODDAARRAA--339900000011
JJUULLYY 22001166

CERTIFICATE
This is to certify that the dissertation entitled,
“PARAMETRIC STUDY OF VARIOUS STRUCTURAL FRAMING
SYSTEMS AND EFFECT OF SUBSTRUCTURE MODELLING ON
SUPERSTRUCTURE”
Submitted by
SOHAIL S DHANPURWALA
in partial fulfillment for the award of degree of
MASTER OF ENGINEERING (CIVIL)
in STRUCTURAL ENGINEERING
to THE MAHARAJA SAYAJIRAO UNIVERSITY OF BARODA, is the record of the
work carried out by him under my supervision and guidance. The matter
presented here, to the best of my knowledge, has not been submitted
earlier for the award of any other degree.
EXTERNAL GUIDE
V. V. SHAH
Deputy Manager
Civil & Steel Structure Department,
LINDE Engineering Pvt. Ltd.,
Vadodara.
INTERNAL GUIDE
Dr. G. S. DOIPHODE
Associate Professor
Applied Mechanics Department,
Faculty of Technology & Engineering,
M. S. University of Baroda,
Vadodara.
HEAD
Dr. B. A. SHAH
Associate Professor
Applied Mechanics Department,
Vadodara.
DEAN
Prof. (Dr.) S. S. BHATTACHARYA
Vadodara.

i
ACKNOWLEGMENTS
I would like to thank those who have contributed to the realization of my thesis
report. This work would not have been possible without the guidance and constant
support of the following persons, to whom I like to express my sincere gratitude.
To begin with, I would like to thank DIPAL OZA (Head, Civil & Steel Structure
Department, Linde Engineering) and VISHAL SHAH (Deputy Manager, Civil & Steel
Structure Department, Linde Engineering) for giving me the opportunity to work on this
project. They are the initiator of this dissertation topic based on “PARAMETRIC STUDY
OF VARIOUS STRUCTURAL FRAMING SYSTEMS AND EFFECT OF SUBSTRUCTURE
MODELLING ON SUPERSTRUCTURE”. During the time working on my thesis he guided
me, was very critical and had given me a lot of feedback, which gave me a better
understanding of the broad subject that this thesis covered.
I also would like to thank VIPUL PATEL (Deputy Manager, Civil & Steel Structure
Department, Linde Engineering) who also guided me, especially in the intermediate
phase of the thesis. During my time working on my thesis at Linde Engineering I got a lot
of support from the wonderful employees. I am also very thankful for the Geotechnical
expert, Dr. KANNAN IYER (Deputy Manager, Civil & Steel Structure Department, Linde
Engineering) who provided me with a lot of practical knowledge in geotechnical
engineering.
I would also like to thank my mentor Dr. G. S. DOIPHODE (Associate Professor,
Applied Mechanics Department) from the Faculty of Technology & Engineering (M.S.
University) for helping me in the starting phase with the documents I had to prepare for
beginning my thesis.
I further extend my thanks to Dr. B. A. SHAH, Head, Applied Mechanics
Department for providing the facilities for research work and extending all help for the
research.
Finally I would like to thank Salim Dhanpurwala my father, Sakina Dhanpurwala
my loving mother. Brothers Roshan and Hussain. I would also like to thank all my friends
at MSU for helping me during my studies in the Vadodara. With your love and support I
was able to finish my study.
July 2016 Sohail S. Dhanpurwala

ii
ABSTRACT
This thesis contains complete study in two parts which is as follows:
Part I (Parametric Study of Various Structural Framing Systems)
Parametric study has been carried out to illustrate the impact of various types of
external loading pattern on various types of structural framing systems. The study
includes parameters such as frame with different support condition, frame with
different height to width ratio, frame with change in elevation of load point, frame
with single bay and multiple bay, frame with different plan bracing system and
different structural systems under action of vertical and horizontal load. Comparison
of deflection and structural weight is done for the selected parameters.
Part II (Effect of Substructure Modelling on Superstructure)
A steel frame has been analysed with different foundation condition to study the
effect of modelling of substructure on superstructure. Plane frame is analysed with
pinned condition at base plate level, fixed condition at the top of foundation,
foundation modelled with plate elements and pile foundation modelled with plate
elements. Winkler‘s spring base is applied in software by assigning nodal springs
having value equal to soil stiffness at the base of discretized plate for isolated
foundation and by assigning nodal springs having value equal to pile stiffness at the
base of discretized plate for pile foundation. The parameters varied for the study are
the modulus of subgrade reaction of the soil, pile stiffness, depth of foundation, height
of superstructure, unsymmetrical gravity load, extent of substructure modelling and
type of connection at interface. A comparison of the displacements of the frame is

iii
done. A comparison of the lateral displacement of top node of the frame is carried out
for each case.
The results of the study will help Structural and other discipline engineers to
understand impact of loads on structure which is essentially required for selection of
right structural system and assessing impact of changes in loads on structures to
adopt overall economical approach for structural arrangement.

iv
Table of Contents
ACKNOWLEGMENTS...........................................................................................................................................i
ABSTRACT...........................................................................................................................................................ii
List of Figures ...................................................................................................................................................vii
List of Tables......................................................................................................................................................ix
List of Graphs.....................................................................................................................................................xi
Notations & Abbreviations ..............................................................................................................................xii
PART - I
INTRODUCTION TO PART I.............................................................................................................................1
GENERAL ..............................................................................................................................................11.1
OBJECTIVE ............................................................................................................................................21.2
SELECTION OF PARAMETERS FOR RESULT COMPARISION ..................................................................31.3
1.3.1 Deflection.............................................................................................................................. 3
1.3.2 Structural weight................................................................................................................... 4
SELECTION OF 2-D FRAME..............................................................................................................................6
INDUSTRIAL PROCESS STRUCTURE ......................................................................................................62.1
STEEL SECTIONS ...................................................................................................................................82.2
STRENGTH AND SEVICEABILITY CHECK................................................................................................92.3
STRUCTURAL SYSTEMS & LOAD ACTIONS................................................................................................ 10
CHAPTER OVERVIEW......................................................................................................................... 103.1
STRUCTURAL FRAMING SYSTEMS..................................................................................................... 103.2
3.2.1 Braced frame (vertical) ....................................................................................................... 10
3.2.2 Moment frame.................................................................................................................... 11
3.2.3 Partial braced frame ........................................................................................................... 13
3.2.4 Combined frame ................................................................................................................. 14
3.2.5 Concrete and steel composite frame.................................................................................. 15
3.2.6 Plan bracing system ............................................................................................................ 16
STRUCTURAL ASPECTS ...................................................................................................................... 173.3
3.3.1 Base condition – Fixed ........................................................................................................ 18
3.3.2 Base condition – Pinned...................................................................................................... 18
FRAMING OPTIONS........................................................................................................................... 193.4
3.4.1 Height to width ratio........................................................................................................... 20
3.4.2 Multiple bay frames............................................................................................................ 21

v
LOAD ACTIONS.................................................................................................................................. 223.5
3.5.1 Vertical load ........................................................................................................................ 22
3.5.2 Horizontal load.................................................................................................................... 24
PARAMETRIC STUDY AND RESULTS.......................................................................................................... 26
EFFECT OF VERTICAL LOAD ON DIFFERENT FRAMING SYSTEM........................................................ 264.1
4.1.1 Moment frame, Combined frame and Partial braced frame comparison.......................... 26
4.1.2 UDL and Point load comparison for moment frame........................................................... 29
EFFECT OF HORIZONTAL LOAD ON DIFFERENT FRAMING SYSTEM .................................................. 334.2
4.2.1 Braced frame, Moment frame, Combined frame and Partial braced frame comparison.. 33
4.2.2 Support condition comparison ........................................................................................... 37
4.2.3 Effect of frame Height to Width ratio................................................................................. 42
4.2.4 Effect of Elevation of Load point......................................................................................... 45
4.2.5 Single bay moment frame and Multiple bay frame comparison........................................ 48
4.2.6 Composite frame and Steel frame comparison.................................................................. 52
4.2.7 Plan bracing system ............................................................................................................ 55
4.2.8 Vertical bracing in frame..................................................................................................... 61

vi
PART - II
INTRODUCTION TO PART II ........................................................................................................................ 65
GENERAL ........................................................................................................................................... 655.1
OBJECTIVE ......................................................................................................................................... 665.2
SOIL MODELS USED IN SOIL STRUCTURE INTERACTION................................................................... 665.3
5.3.1 NUMERICAL MODELS.......................................................................................................... 67
LITERATURE REVIEW................................................................................................................................... 71
PRELIMINARY REMARK ..................................................................................................................... 716.1
LITERATURE STUDIED........................................................................................................................ 716.2
MODELLING AND ANALYSIS ........................................................................................................................ 77
METHODOLOGY ................................................................................................................................ 777.1
CODAL PROVISIONS .......................................................................................................................... 797.2
PARAMETRIC STUDY & RESULTS............................................................................................................... 81
TYPE OF SOIL ..................................................................................................................................... 828.1
DEPTH OF FOUNDATION................................................................................................................... 878.2
HEIGHT OF SUPERSTRUCTURE AND TYPE OF ANALYSIS ................................................................... 918.3
8.3.1 Height of superstructure..................................................................................................... 91
8.3.2 Type of analysis................................................................................................................... 96
UNSYMMETRICAL GRAVITY LOAD..................................................................................................... 998.4
TYPE OF CONNECTION AT INTERFACE ............................................................................................ 1048.5
PILE MODELING............................................................................................................................... 1088.6
DECISION MATRIX....................................................................................................................................... 112
FUTURE SCOPES.............................................................................................................................. 1149.1
REFERENCES........................................................................................................................................... 115

Parametric Study of various Structural Framing Systems Page vii
List of Figures
FIG. 1 OVERVIEW OF PIPE RACK ....................................................................................................... 7
FIG. 2 OVERVIEW OF TECHNOLOGICAL STRUCTURE.......................................................................... 7
FIG. 3 TYPES OF BRACED FRAMES .................................................................................................. 11
FIG. 4 MOMENT FRAME................................................................................................................... 12
FIG. 5 PARTIAL BRACED FRAME ..................................................................................................... 13
FIG. 6 COMBINED FRAME ................................................................................................................ 14
FIG. 7 COMPOSITE FRAME............................................................................................................... 15
FIG. 8 ALTERNATIVE PLAN BRACING ARRANGEMENT .................................................................... 17
FIG. 9 BASE CONDITION - FIXED ..................................................................................................... 18
FIG. 10 BASE CONDITION - PINNED ................................................................................................. 19
FIG. 11(A) 3 TIER FRAME ................................................................................................................ 20
FIG. 11(B) 2 TIER FRAME ................................................................................................................ 20
FIG. 12(A) SINGLE BAY FRAME....................................................................................................... 21
FIG. 12(B) MULTIPLE BAY FRAME .................................................................................................. 21
FIG. 13 UNIFORMLY DISTRIBUTED LOAD (UDL) ............................................................................ 23
FIG. 14 POINT LOAD........................................................................................................................ 23
FIG. 15 FRAME WITH HORIZONTAL / LATERAL LOAD...................................................................... 25
FIG. 16 FRAMING SYSTEMS SUBJECTED TO UDL ............................................................................ 26
FIG. 17 MOMENT FRAMES WITH UDL & POINT LOAD .................................................................... 29
FIG. 18 DEFLECTION & STRENGTH RATIO COMPARISON................................................................. 30
FIG. 19 FRAMING SYSTEMS SUBJECTED TO HORIZONTAL LOAD ..................................................... 33
FIG. 20 FRAMES WITH FIXED & PINNED SUPPORT CONDITION........................................................ 37
FIG. 21 STRENGTH RATIO COMPARISON........................................................................................... 38
FIG. 22 COLUMN SIZE COMPARISON ................................................................................................ 39
FIG. 23 SUPPORT REACTION............................................................................................................ 40
FIG. 24 FRAMES WITH SAME USEABLE SPACE................................................................................. 42
FIG. 25 FRAMES WITH CHANGE IN ELEVATION OF LOAD POINT...................................................... 45
FIG. 26 SINGLE BAY & MULTIPLE BAY MOMENT FRAME............................................................... 48
FIG. 27 COMPOSITE FRAME & STEEL FRAME .................................................................................. 52

viii
FIG. 28 FRAME WITH NO PLAN BRACING ........................................................................................ 55
FIG. 29 DIFFERENT PLAN BRACING SYSTEM ................................................................................... 56
FIG. 30 PLAN VIEW OF FRAMES FOR STRUCTURAL WT. COMPARISON............................................ 59
FIG. 31 SIGN CONVENTION FOR SUPPORT REACTION ...................................................................... 63
FIG. 32 MODELLING OF FOUNDATION ............................................................................................. 78
FIG. 33 FRAMES WITH DIFFERENT BASE SUPPORT .......................................................................... 81
FIG. 34 SELECTED FRAME FOR CASE 8.1......................................................................................... 83
FIG. 36 SELECTED FRAMES FOR CASE 8.3 ....................................................................................... 92
FIG. 37 SECOND-ORDER EFFECTS IN A VERTICAL CANTILEVER ...................................................... 96
FIG. 39 SELECTED FRAME FOR CASE 8.5....................................................................................... 104
FIG. 40 PILE MODELLING WITH SPRING AT REGULAR INTERVAL .................................................. 108
FIG. 41 PILE MODELLED AS EQUIVALENT SINGLE SPRING SUPPORT............................................. 109
FIG. 42 FRAMES WITH FULL PILE MODELLED & SINGLE POINT PILE STIFFNESS ........................... 109
FIG. 43 DECISION MATRIX ............................................................................................................ 113

ix
List of Tables
TABLE 1 STRUCTURAL WT. COMPARISON FOR FRAMES SUBJECTED TO UDL .................................. 28
TABLE 2 STRUCTURAL WT. COMPARISON FOR FRAMES WITH UDL & POINT LOAD......................... 31
TABLE 3 DEFLECTION COMPARISON FOR FRAMES SUBJECTED TO HORIZONTAL LOAD..................... 34
TABLE 4 STRUCTURAL WT. COMPARISON FOR FRAMES SUBJECTED TO HORIZONTAL LOAD ............ 35
TABLE 5 DEFLECTION COMPARISON FOR FIXED & PINNED BASE FRAME......................................... 38
TABLE 6 STRUCTURAL WT. COMPARISON FOR FIXED & PINNED BASE FRAME ................................ 39
TABLE 7 REACTION COMPARISON FOR FIXED & PINNED BASE FRAME ............................................ 40
TABLE 8 DEFLECTION COMPARISON FOR FRAMES WITH SAME USEABLE SPACE ............................... 43
TABLE 9 STRUCTURAL WT. COMPARISON FOR FRAMES WITH SAME USEABLE SPACE ...................... 44
TABLE 10 DEFLECTION COMPARISON FOR CHANGE IN ELEVATION OF LOAD POINT ......................... 46
TABLE 11 STRUCTURAL WT. COMPARISON FOR CHANGE IN ELEVATION OF LOAD POINT................. 47
TABLE 12 DEFLECTION COMPARISON FOR SINGLE BAY & MULTIPLE BAY FRAME........................... 49
TABLE 13 STRUCTURAL WT. COMPARISON FOR SINGLE BAY & MULTIPLE BAY FRAME.................. 50
TABLE 14 DEFLECTION COMPARISON FOR COMPOSITE & STEEL FRAME ......................................... 53
TABLE 15 STRUCTURAL WT. COMPARISON FOR COMPOSITE & STEEL FRAME................................. 54
TABLE 16 DEFLECTION COMPARISON FOR FRAME WITHOUT PLAN BRACING ................................... 57
TABLE 17 DEFLECTION COMPARISON FOR FRAME WITH X-TYPE PLAN BRACING ............................. 57
TABLE 18 DEFLECTION COMPARISON FOR FRAME WITH GIRDER TYPE PLAN BRACING .................... 57
TABLE 19 DEFLECTION COMPARISON FOR FRAME WITH DIAMOND TYPE PLAN BRACING................. 57
TABLE 20 HORIZONTAL DRIFT RATIO COMPARISON FOR FRAMES WITH OR WITHOUT PLAN BRACE. 58
TABLE 21 STRUCTURAL WT. COMPARISON FOR FRAMES WITH & WITHOUT PLAN BRACING............ 59
TABLE 22 SUPPORT REACTION COMPARISON FOR (+ VE) FORCES .................................................... 64
TABLE 23 SUPPORT REACTION COMPARISON FOR (- VE) FORCES ..................................................... 64
TABLE 24 SELECTED SUBGRADE MODULUS.................................................................................... 83
TABLE 25 FOUNDATION DETAILS FOR FRAME IN FIG. 34 ................................................................ 83
TABLE 26 CHANGE IN DEFLECTION WITH TYPE OF SOIL [ISOLATED FOUN.].................................... 84
TABLE 27 SELECTED PILE STIFFNESS.............................................................................................. 85
TABLE 28 CHANGE IN DEFLECTION WITH TYPE OF SOIL [PILE FOUN.] ............................................ 86
TABLE 29 FOUNDATION DETAILS FOR FRAME IN FIG. 35 ................................................................ 88
TABLE 30 CHANGE IN DEFLECTION WITH DEPTH OF FOUN. [ISOLATED FOUN.]............................... 89

x
TABLE 31 CHANGE IN DEFLECTION WITH DEPTH OF FOUN. [PILE FOUN.]........................................ 90
TABLE 32 FOUNDATION DETAILS FOR FRAMES IN FIG. 36 .............................................................. 91
TABLE 33 CHANGE IN DEFLECTION WITH HT. OF SUPERSTRUCTURE [ISOLATED FOUN.- 1ST
ORDER] . 94
TABLE 34 CHANGE IN DEFLECTION WITH HT. OF SUPERSTRUCTURE [PILE FOUN. -1ST
ORDER].......... 95
TABLE 35 CHANGE IN DEFLECTION WITH HT. OF SUPERSTRUCTURE [ISOLATED FOUN. - 2ND
ORDER] 97
TABLE 36 CHANGE IN DEFLECTION WITH HT. OF SUPERSTRUCTURE [PILE FOUN. - 2ND
ORDER] ........ 98
TABLE 37 FOUNDATION DETAILS FOR FRAME IN FIG. 38 .............................................................. 100
TABLE 38 CHANGE IN DEFLECTION WITH UNSYMMETRICAL LOAD [ISOLATED FOUN.]................. 101
TABLE 39 INCREASE IN DEFLECTION DUE TO UNSYMMETRICAL LOAD [ISOLATED FOUN.]........... 101
TABLE 40 CHANGE IN DEFLECTION WITH UNSYMMETRICAL LOAD [PILE FOUN.] ......................... 102
TABLE 41 INCREASE IN DEFLECTION DUE TO UNSYMMETRICAL LOAD [PILE FOUN.].................... 103
TABLE 42 FOUNDATION DETAILS FOR FRAME IN FIG. 39 .............................................................. 105
TABLE 43 CHANGE IN DEFLECTION WITH CONNECTION TYPE [ISOLATED FOUN.]......................... 106
TABLE 44 CHANGE IN DEFLECTION WITH CONNECTION TYPE [PILE FOUN.] ................................. 106
TABLE 45 PILE STIFFNESS AT DIFFERENT DEPTH.......................................................................... 110
TABLE 46 SINGLE POINT PILE SPRING STIFFNESS ......................................................................... 111
TABLE 47 DEFLECTION COMPARISON FOR FRAME WITH DIFFERENT PILE MODEL........................ 111

xi
List of Graphs
GRAPH 1 STRUCTURAL WT. COMPARISON FOR FRAMES SUBJECTED TO UDL.................................. 28
GRAPH 2 STRUCTURAL WT. COMPARISON FOR FRAMES WITH UDL & POINT LOAD ........................ 32
GRAPH 3 DEFLECTION COMPARISON FOR FRAMES SUBJECTED TO HORIZONTAL LOAD ................... 34
GRAPH 4 STRUCTURAL WT. COMPARISON FOR FRAMES SUBJECTED TO HORIZONTAL LOAD........... 35
GRAPH 5 DEFLECTION COMPARISON FOR FIXED & PINNED BASE FRAME ........................................ 38
GRAPH 6 STRUCTURAL WT. COMPARISON FOR FIXED & PINNED BASE FRAME................................ 39
GRAPH 7 DEFLECTION COMPARISON FOR FRAMES WITH SAME USEABLE SPACE .............................. 43
GRAPH 8 STRUCTURAL WT. COMPARISON FOR FRAMES WITH SAME USEABLE SPACE...................... 44
GRAPH 9 DEFLECTION COMPARISON FOR CHANGE IN ELEVATION OF LOAD POINT........................... 46
GRAPH 10 STRUCTURAL WT. COMPARISON FOR CHANGE IN ELEVATION OF LOAD POINT ................ 47
GRAPH 11 DEFLECTION COMPARISON FOR SINGLE BAY & MULTIPLE BAY FRAME.......................... 49
GRAPH 12 STRUCTURAL WT. COMPARISON FOR SINGLE BAY & MULTIPLE BAY FRAME ................. 50
GRAPH 13 DEFLECTION COMPARISON FOR COMPOSITE & STEEL FRAME......................................... 53
GRAPH 14 STRUCTURAL WT. COMPARISON FOR COMPOSITE & STEEL FRAME................................ 54
GRAPH 15 DRIFT RATIO COMPARISON FOR FRAMES WITH OR WITHOUT PLAN BRACE...................... 58
GRAPH 16 STRUCTURAL WT. COMPARISON FOR FRAMES WITH & WITHOUT PLAN BRACING ........... 60
GRAPH 17 DEFLECTION V/S TYPE OF SOIL [ISOLATED FOUN.]......................................................... 84
GRAPH 18 DEFLECTION V/S PILE STIFFNESS [PILE FOUN.]............................................................... 85
GRAPH 19 DEFLECTION V/S DEPTH OF FOUNDATION [ISOLATED FOUN.] ......................................... 89
GRAPH 20 DEFLECTION V/S DEPTH OF FOUNDATION [PILE FOUN.].................................................. 89
GRAPH 21 DEFLECTION V/S SUPERSTRUCTURE HEIGHT [ISOLATED FOUN.] .................................... 93
GRAPH 22 DEFLECTION V/S SUPERSTRUCTURE HEIGHT [PILE FOUN.]............................................. 94
GRAPH 23 DEFLECTION V/S SUPERSTRUCTURE HEIGHT [ISOLATED FOUN. - 2ND
ORDER] ................. 97
GRAPH 24 DEFLECTION V/S SUPERSTRUCTURE HEIGHT [PILE FOUN. - 2ND
ORDER] ......................... 98
GRAPH 25 DEFLECTION V/S UNSYMMETRICAL LOAD [ISOLATED FOUN.]...................................... 101
GRAPH 26 DEFLECTION V/S UNSYMMETRICAL LOAD [PILE FOUN.] ............................................... 102
GRAPH 27 DEFLECTION V/S CONNECTION AT INTERFACE [ISOLATED FOUN.]................................ 105
GRAPH 28 DEFLECTION V/S CONNECTION AT INTERFACE [PILE FOUN.] ........................................ 106

xii
Notations & Abbreviations
 For column beam framing connection, shows rigid connection (moment connection).
 For column beam framing connection, shows simple connection (shear connection).
 In different structural framing system, or shows bracing member.
 RCC : Reinforced Cement Concrete
 WT. or Wt. : Weight
 Ht. : Height
 foun. : Foundation
Notes:
 All dimensions are in Meters except specified.
 All loads are in kN except specified.
 Deflection values are in mm.

Parametric Study of various Structural Framing Systems Page 1
INTRODUCTION TO PART I
GENERAL1.1
The process of designing a structural framing system in plant involves lot of
consideration and coordination between different disciplines and groups involved in the
project. The major groups involve are Process, Piping, Stress, Static & Rotating
equipment, Electrical & Instrumentation and Civil & steel structural. The initial study
begins with Process department which gives input in the form of Piping &
Instrumentation diagram and 2D-layout to piping department. Piping department does
preliminary 3D modelling, which is input for stress department. The stress department
performs the stress analysis for critical lines and calculates the load generated by the
critical lines, which is then passed to the civil & structural department. Civil & Structural
department designs the foundation based on the load input received from stress
department. The structural design is incorporated in the other discipline to check if it is
acceptable with them. If there are any constraints in the design by any discipline the
points are discussed & mutually agreed and resolved respectively. The finalization of the
design will require the above to be repeated again & again.
In all the projects, often the final piping, raceway and equipment information are
available at later stage of project. Civil & steel structural department is the last to get
input and need to give output first. Thus, civil & structural department use judgment
based on experience when applying or allowing for loads that are not known, justifying
CHAPTER 1

Introduction to Part I Chapter 1
them in the design basis under design philosophy. But at the later stage of the project
when all the load details become available, actual load values may contradict with the
load values used for design thus, there is need for redesign. Parametric study of
structural framing systems commonly encountered in industrial plants has been carried
out. It explains the behaviour of different framing system under different load actions.
Up to certain extent, this study will be helpful to know the effect of revised input (new
load values) on the structural frame. This dissertation work helps in identifying better
structural framing system from selected for study under various conditions.
OBJECTIVE1.2
This study intends to explain effect of different types of external loading patterns on
various types of structural framing systems. Parametric study has been carried out to
illustrate the effect. The results of the study will help Structural and other discipline
engineers to understand impact of loads on structure, which is essentially required for
selection of right structural system and assessing impact of changes in loads on
structures to adopt overall economic approach for structural arrangement. The study
includes parameters such as change in value of horizontal load, change in form of vertical
load, change in elevation of horizontal point load on structural framing system etc. Such
study will help structural engineer to understand the impact of change in these
parameters on structural framing system and it will also be helpful to structural to take
decision of any change in parameter.

SELECTION OF PARAMETERS FOR RESULT COMPARISION1.3
Values of top point lateral displacement and structural weight for different structural
framing systems are evaluated and compared. Structural framing weight is compared to
check economy of the structural system and Deflection is compared as it impacts main
component of the plant i.e. equipment & piping. Excessive deflection also impacts
structural and functional requirement of the framing system.
1.3.1 Deflection
Due to lateral deflection of frame there will be loss of serviceability. Loss of serviceability
includes misalignment of piping and industrial equipment. In pressure piping, pipe
risers may fail due to inter-story drift between adjacent floors, that is, differential
movement between the points of support located on different floors of the building. Or
else instead of whole failure the pipes or pipe joints may fail and leak. Improperly
supported pipes can become dislodged and fall. Joints may fail due to sway of frame in
floor mounted pipes. Also differential settlement can lead to excessive internal forces /
stresses in piping.
Piping system account for a significant portion of the total plant cost, at times as much as
one-third of the total investment. Pipe rack failures could cause serviceability problems
for plant operations. Failures of pipe support systems could potentially impact the
health, welfare, and safety of plant personnel due to pipe breakage or leaks. The failure of
pipe supports or excessive deflection of support may result into following problems with
piping:

 Piping stresses in excess of those permitted in the Code.
 Leakage at joints.
 Excessive thrusts and moments on connected equipment.
 Excessive interference with thermal expansion and contraction in piping.
 Unintentional disengagement of piping from its supports.
The lateral deflection value has a particular importance of serviceability requirement.
The following problems are associated with large values of lateral deflection.
 Structural damage: Deflection related investigations have shown that during
earthquake, large damage potential is observed with large values of deflection
irrespective of design and detailing of the structure.
 Non – structural damage: Larger deflection may damage the cladding; create
problems like bending of doors and windows frames.
 Discomfort to occupants: The occupants feel discomfort with the large lateral
deflection / drift although no structural damages are observed.
1.3.2 Structural weight
Selection of an appropriate structural framing system in steel structures is one of the
important factor affecting the weight of consumed steel and consequently, the economics
of the project. The study involves comparison of structural weight of different framing
system, comparison of same structural system with different structural aspect. In other
words, it is attempted to evaluate and compare the weight of consumed steel. Today, one
of the indicators that affect the quality of construction is final cost. Consequently, one of

the criteria for design of the structure is to reduce weight and making the plant more and
more economical. In steel structures with the industrial utility, weight of consumed steel
is an appropriate basis for decision of investors and constructors. Weight of consumed
steel in steel structures is affected by structural system. Therefore, selection of a suitable
structural system is one of the important and effective decisions in achieving economy of
the project.

SELECTION OF 2-D FRAME
INDUSTRIAL PROCESS STRUCTURE2.1
Pipe rack and Technological structure are commonly encountered in oil and gas industry.
Pipe rack is used to carry pipes (process and utility) to process area. Technological
structure is used to support process equipment and their connected piping. Generally, in
pipe rack, transverse frames are spaced at 5.0 – 7.0 m, this spacing is chosen based on
the maximum allowable spans for the pipes or cable trays being supported. Spacing can
vary based on the estimated size and allowable deflection limits of the pipe being
supported.
Longitudinal struts are usually offset from the beams used to support the pipes. Levels of
the pipe rack are assumed to be fully loaded with pipe, and when the pipes need to exit
the rack to the side to connect to equipment, a flat turn cannot be used as this would
clash with the other pipes on the same level. The pipe is typically routed to turn either up
or down and then out of the rack at the level of the longitudinal struts where the pipe can
be supported on the longitudinal struts before exiting the rack. In technological
structure, spacing of structural frames is decided based on layout of the equipment on
the structure and ground.
Fig. 1 and Fig. 2 shows an isometric view of the pipe rack and technological (equipment
supporting) structure respectively.
CHAPTER 2

Selection of 2-D frame Chapter 2
Fig. 1 Overview of Pipe Rack
Fig. 2 Overview of Technological structure
The typical frame is chosen and modelled based on idealized conditions. A width of
6.0 m is chosen to allow one-way traffic along corridor. The height of the first level of the
structure is set at 5.0 m to provide sufficient height clearance along the access corridor.
In this study spacing between two transverse frames is set as 6.0 m c/c. Here 2-D frames

selected for the study are assumed to be braced in minor direction and effect of same is
considered in the design.
Based on D. A. Nelson (W. W. University, 2008) results of the isolated moment frame
and the entire pipe rack segment, relatively small differences were observed. Because the
braced bay supports any longitudinal loading, relatively very little weak axis column
moment or longitudinal deflection occurs that would affect the design of the columns or
beams that are part of the transverse frame. Ratios of demand to capacity showed errors
of less than 5% on member design, when using the single frame compared to the full pipe
rack structure. Therefore, analysis of a single transverse frame will be used to simplify
calculations. 2-D frames are used for the study of the behaviour of framing
arrangements. However, derived conclusions and underlining principles are applicable
to 3-D structures. Hence, concepts explained in the different cases can be applied by
engineers suitably to plant structures.
STEEL SECTIONS2.2
European steel sections are used throughout this study. Equal angle sections are used for
bracing member and I – section are used for column and beam members. In this study
HE sections are used, which are classified as A, B and M e.g. HE200A, HE200B and
HE200M respectively. HE _A sections are only used in this thesis.

STRENGTH AND SEVICEABILITY CHECK2.3
Strength and serviceability checks are performed in STAAD.Pro V8i, where RATIO
parameter (Permissible ratio of actual load to allowable load) is set to be 1.0. The
strength checks are based on AISC 360-05.
Serviceability checks are made using the calculated deflections from STAAD.Pro V8i.
Various limits on serviceability are based on specific project requirements. For checking
serviceability criteria adopted deflection as per AISC 360-05 limits are:
 For horizontal drift = Height/200 [AISC Cl. L4]
 For vertical deflection = Length/360 [AISC Cl. L]

STRUCTURAL SYSTEMS & LOAD ACTIONS
CHAPTER OVERVIEW3.1
The different structural framing systems which are commonly used in the industrial
plants have been selected for study and are explained in this chapter as mentioned
below:
 Braced frame (Vertical / Elevation)
 Moment frame
 Partial braced frame
 Combined frame
 Composite frame
 Plan bracing system
The brief information on different types of support conditions at base plate level and
different framing options is also included in this chapter. This chapter also covers
different load actions on these structural framing systems, which are of horizontal and
vertical point loading and UDL respectively.
STRUCTURAL FRAMING SYSTEMS3.2
3.2.1 Braced frame (vertical)
A Braced frame is a structural system, which is designed primarily to resist lateral
forces i.e. wind and earthquake forces. Bracing members in the frame are designed to
resist tension and compression, which is same as truss. As per literature braced frames
have much higher initial strength and stiffness. Bracing is a much effective than rigid
CHAPTER 3

Structural systems & Load actions Chapter 3
joints at resisting deformation of the frame. Braced frames use less material and have
simpler connections than moment-resisting frames. Fig. 3 shows different braced
frames.
Fig. 3 Types of Braced Frames
The bracing members can be arranged in different forms to carry solely tension or
alternatively tension and compression. When it is designed to take tension only, the
bracing is made up of crossed diagonals. Depending on the wind direction, one diagonal
will take all the tension while the other remains inactive. Tensile bracing is smaller than
the equivalent strut and is usually made up of flat - plate, channel or angle sections and
rod. When designed to resist compression, the bracings become struts and the most
common arrangement is the ‗K‘ brace/Chevron bracing.
3.2.2 Moment frame
Moment frames are rectilinear assemblages of beams and columns, with the beams
rigidly connected to the columns. Moment frame involves constructing very rigid beam-

to-column connections that permit moment transfer across the joint. Resistance to
lateral forces is provided primarily by rigid frame action - that is, by the development
of bending moment and shear force in the frame members and joints. By virtue of the
rigid beam-column connections, a moment frame cannot displace laterally without
bending the beams or columns depending on the geometry of the connection. The
bending rigidity and strength of the frame members is therefore the primary source of
lateral stiffness and strength for the entire frame. Fig. 4 shows Moment frame.
Fig. 4 Moment Frame
A typical moment-resisting beam-to-column steel-framed connection involves
transferring horizontal loads through the beam flanges directly to the column flanges by
using angles and column web stiffener plates. The analysis of the connection is fairly
complex, labour-intensive and expensive to construct and is not as good as other

methods of stabilization. In comparison with braced frames, moment frames have more
deformation capacity with less stiffness.
3.2.3 Partial braced frame
Partial braced frame can be obtained by providing an element called "knee" in between
the beam and column. Partial braced frames are modified form of braced frame in which
braced element is cut short and connected to the adjacent column. The key component of
the Partial braced frame is the knee element, which controls the initial elastic stiffness of
the frame and also limits interstorey drifts. Moment at the beam-column junction may
be released partially or fully. Fig. 5 shows Partial braced frame.
Fig. 5 Partial Braced Frame
Due to vertical (gravity) load, knee bracing is under compression and due to lateral load;
knee bracing is under compression or tension, depending upon the direction of the
lateral load. Hence, knee bracing and its connection with the beam-column are to be

designed for compressive load as well as for tensile loads. In the beam and column, at the
junction of knee bracing, the design force in the knee bracing may be resolved in two
components i.e. horizontal and vertical. These components will cause bending in the
beam and column. Hence, beam and column are to be designed for bending at the
junction of knee bracing.
3.2.4 Combined frame
This framing system provides resistance to lateral loads and provides stability to the
structural system, by combination of bracing and rigid connection. This frame can be
used to reduce horizontal deflection. The key component of the combined frame is the
bracing in the bottom storey, which provides higher initial strength and stiffness to the
complete frame.
Fig. 6 Combined Frame
Combined frame is very useful where lateral load at bottom storey is higher compared to
all other storey. This structural system can also be used where height of bottom story is

quiet more compared to other storey and bottom storey column governs in slenderness.
Fig. 6 shows Combined frame.
3.2.5 Concrete and steel composite frame
In this framing system, lower part is made of RCC column. Pinned condition is
considered at RCC and steel column junction. The frame shown in Fig. 7 is a Composite
frame. The concrete column in bottom part increases stiffness of the frame. Due to
higher stiffness of concrete part, deflection at top node is less compared to steel frame.
This structural system is very useful where there is fire resistance requirement in the
bottom part of the frame. The concrete part can be either column only or it can have
concrete frame where the beam can be either be simply supported or console (in case of
precast) or have rigid connection with column.
Fig. 7 Composite Frame

3.2.6 Plan bracing system
In most commercial buildings, floor and roof diaphragms are used to distribute loads in
the horizontal plane of the structure to the lateral load resisting system. Due to the open
nature of most industrial structures, diaphragms are not present, and horizontal bracing
is often used to distribute the loads in the horizontal plane. Horizontal bracing is also
used in heavily loaded commercial structures, where a diaphragm is not present, or
where the strength or stiffness of the diaphragm is not adequate. When horizontal
bracing is used, the beams at that elevation become members in a horizontal truss
system, carrying axial loads in addition to the normal bending and shear loads. From
design point of view attention should be paid to the beam end connections within the
truss system, because the axial loads transferring through the connections is of higher
magnitude. A bracing system contributes to the distribution of load and provides
restraint to compression flanges or chords where they would otherwise be free to buckle
laterally. A small tonnage of steel bracing can be used to provide huge increases in the
bending resistance of the main beams. Plan bracing is perhaps the most obvious way to
prevent lateral buckling of a compression flange and plan bracing also provides lateral
restraint, i.e. it restrains the compression flanges of beams from moving sideways. Plan
bracing takes the form of diagonal members, usually angle sections, connecting the
compression flanges of the main beams, to form a truss when viewed in plan. This makes
a structure very stiff in response to lateral movement. Most plan bracing will be at top

flange level. Error! Reference source not found. shows different plan bracing
arrangements.
Without bracing, beams vulnerable to buckling
With plan bracing, buckling is controlled
Fig. 8 Alternative Plan Bracing Arrangement
STRUCTURAL ASPECTS3.3
There are two base conditions – fixed and pinned which are considered for the study. In
the study base condition refers to support condition at the base plate level in the framing
system. Detailed description is given below.

3.3.1 Base condition – Fixed
A fixed base column is more of a special situation base connection, has a lot of stiffness
which resist horizontal, vertical, and moment loads. The additional stiffness at the base
and in the columns, means less stiffness is required from the rest of the building
members. The foundations may need to be larger than the pinned base because of
moment transferred at base. The fabrication and installation of fixed base columns can
also be more difficult because of the additional plates on the column and anchor rods
required. Typically, fixed base columns are recessed below finished floor. The Fig. 9
shows fixed base column. There are a few options for this condition depending on the
size of the building and the loading.
Fig. 9 Base Condition - Fixed
3.3.2 Base condition – Pinned
A pinned base column is the standard column base found in most steel buildings. This
connection is pinned because it has enough stiffness to apply horizontal and vertical

loads to the foundations, but enough flexibility not to apply moment. Due to loading
when deflection requirements is very stringent, pinned base will require much more steel
than fixed base. The pinned base is typically very easy to install. Pinned base will have
smaller foundation size compared to fixed based. For pinned base condition, anchor
bolts are placed within section of column while for fixed base connections, anchor bolts
are placed outside the section. So higher pedestal sizes are expected in case of fixed base
conditions. Fig. 10 shows pinned type base connection.
Fig. 10 Base Condition - Pinned
FRAMING OPTIONS3.4
Two framing options namely frames with different height to width ratio and multiple bay
frames are considered in the present study. These two framing options are explained in
detail below.

3.4.1 Height to width ratio
An elevated multi-level pipe rack may be required for plant layout, equipment or process
reasons. As long as the required space beneath the pipe rack for accessibility and road
crossings has been taken into account, the rack can remain single level. However, in
most cases, multiple levels will be required. Within plant units, most process pipes are
connected to related unit equipment. Placing these pipes in the lower levels results in
shorter pipe runs, savings on piping costs and better process flow conditions. In this
aspect of structural system effect of frame height to width ratio has been checked.
Useable space of the frame is kept same while height and width are changed.
(a) 3 Tier Frame (b) 2 Tier Frame
Fig. 11
If horizontal clearance is available, width of the transverse frame is increased and
number of tiers can be decreased. But if sufficient space is not available one can decrease
the width and increase number of tier as per requirement. Example for the same is as

shown above. 3 tier-6.0 m wide transverse frame is shown in Fig. 11.a, useable space in
this frame is 18 m. 2 tier-9.0 m wide transverse frame is shown Fig. 11.b, useable space in
this frame is 18 m. Useable space in both the frames shown in Fig. 11 is almost same but
height to width ratio for 3 tier - 6.0 m wide frame is 1.83 (i.e. 11/6) and that for 2 tier -
9.0 m wide frame is 0.89 (i.e. 8/9) .
3.4.2 Multiple bay frames
In this aspect of structural system effect of number of bays has been checked. Useable
space of the frame is kept same while comparing number of bays. Example for the same
is shown below. Fig. 12.a shows 1 bay – 9.0m wide frame having useable space of 27.0 m
and Fig. 12.b shows 2 bays – 5.0m wide frame having useable space of 30.0 m. But
useable space for both the frames is almost same as second frame involves one additional
column. Multiple bay frame will require one additional foundation per every increase of
one additional bay while steel sections are lighter in multi bay frame.
(a) Single bay frame (b) Multiple bay frame
Fig. 12

LOAD ACTIONS3.5
In oil and gas sector structures are different than general building structures. Moreover,
frames have different loading as compared to general buildings structure. For these
structures, certain types of loading (e.g. piping load, equipment loads, etc…) are not
clearly mentioned in standard codes. These structures resist gravity loads as well as
lateral loads from either pipes, equipments, cable trays or wind and seismic loads. Loads
present in these kind of structures includes Dead Load (DL) of the structure, Live Load
(LL) on the structure, Temperature Load on Structure, Earthquake Load, Wind Load,
Pipe/ equipment Load (empty, operating & hydro test), Pipe Anchor / Guide Load, Pipe
Friction Load, Cable tray loads, etc.
3.5.1 Vertical load
The vertical load includes, Dead Load of the structure, Live Load on the structure, Pipe /
equipment (Empty, Operating, Hydro test), cable trays load, etc. These vertical loads can
be generated in the form of uniformly distributed load or Point load.
a. Uniformly Distributed Load (UDL)
At proposal stage of engineering, getting actual "Point loads" of all critical/non critical
lines is difficult and time consuming. So at this stage of project, generally loading is
available in the form of UDL (Typically Pipe size 10" and below). During stage of detail
engineering also, loads of small-bore lines (typically 6‖ below) available in the form of
UDL. For small-bore line, having loads in form of UDL is advantages because it will take
care of change in size/location of pipe or spacing between pipes. For example, in a bunch

of 7 lines, if some line sizes increase/decrease effective change in UDL would be less and
in case of change in the spacing between pipes changes or line is moved across the
section of rack, the UDL will have no or little changes. The example of uniformly
distributed load (UDL) is shown in Fig. 13 with beam having UDL throughout its span.
Fig. 13 Uniformly Distributed Load (UDL)
b. Point load
As the project develops, actual loads and locations become known, the structural design
should be carried out based on the actual data. Generally, a concentrated load should be
added for pipes that are 300 mm (12 inch) and larger in diameter. This assumption
needs to be verified by piping group for each project. The beam with point load /
concentrated load is shown in Fig. 14.
Fig. 14 Point Load
q 0
q 0
P
P

3.5.2 Horizontal load
Earthquake load, Wind load, Temperature load on structure, Pipe Anchor / Guide load,
Pipe Friction load etc. are considered as horizontal load acting on the structure. Wind
load on structural members, piping, electrical trays, equipment, platforms, and ladders
should be determined in accordance with project approved design code. Horizontal wind
should typically be applied to structural framing, cable tray vertical drop (if any), large
diameter pipes vertical drop (if any) and equipment only. The effects of longitudinal
wind on piping and trays running parallel to the wind direction should be neglected.
Seismic forces generated by the pipes, raceways, supported equipment, and structure
should be considered and should be based on their operating weights. Friction forces
caused by hot lines sliding across the pipe support during startup and shutdown are
assumed to be partially resisted through friction by nearby cold lines. Therefore nominal
unbalance friction force acting on a pipe support is considered in the design. Friction
between piping and supporting steel should not be relied upon to resist wind or seismic
loads. Industrial structures in oil and gas sector should be checked for anchor and guide
loads as determined by the pipe stress group. It may be necessary to use horizontal
bracing if large anchor forces are encountered. In this study horizontal load is applied
only in X-direction (major axis of the section).

Fig. 15 Frame with Horizontal / Lateral Load

PARAMETRIC STUDY AND RESULTS
The present work attempts to study impact of load action on different framing system. As
mentioned in chapter 1, two parameters namely Deflection and Structural weight of
different framing system like Moment frame, Braced frame, Partial braced frame,
Combined frame and Composite frame are compared. Structural weight is compared to
check economy of the structural system and deflection is compared as it impacts main
component of the plant i.e. piping as explained in previous chapter. Comparison of
different structural framing system along with different structural aspects is mentioned
below.
EFFECT OF VERTICAL LOAD ON DIFFERENT FRAMING SYSTEM4.1
4.1.1 Moment frame, Combined frame and Partial braced frame
comparison (subjected to vertical load)
A-1 A-2 A-3
Moment frame Combined frame Partial braced frame
Fig. 16 Framing Systems Subjected to UDL
CHAPTER 4

Parametric study & Results Chapter 4
In this case three different framing systems, Moment frame (A-1), Combined frame (A-2)
and Partial braced frame (A-3) have been selected and vertical load in form of UDL is
applied as shown in Error! Reference source not found. and height of each frame is
11.0 m. Generally in the industrial process structure process lines are passing through
bottom most tier and utility lines and cable tray are placed on tier above that, hence first
tier in the above framing systems is loaded with higher load compared to second and
third tier. The load on the first tier is 6.0 kN/m2 and that on second and third tier is 3.0
kN/m2. As structural frame are considered to be spaced at 6.0 m c/c, the load applied
during analysis is 36 kN/m on first tier and 18 kN/m on second and third tier in the form
of uniformly distributed load. Effect on structural weight is studied by satisfying
Strength and serviceability criteria for above framing systems. Serviceability is checked
for the beam member by restricting the vertical deflection to span/360 while stress ratio
(utilization of member strength) is restricted to 1.0 in order to satisfy strength criteria for
every member in the frame. Results of structural weight comparison are shown below in
Table 1 as well as in graphical form in Graph 1. Here P-1 and P-2 is applied vertical load
to the frame. Following points are observed from Table 1:
 For same load, structural weight of frame A-3 (Partial braced frame) is least while
that of frame A-1 (moment frame) is highest.
 Structural weight required for moment frame is 12% more compared to Partial braced
frame.

Table 1 Structural Wt. comparison for frames subjected to UDL
P-1
(kN/m2)
P-2
(kN/m2)
STRUCTURAL WEIGHT (kg)
(A-1)/(A-2) (A-1)/(A-3) (A-2)/(A-3)
A-1 A-2 A-3
3 6 1856 1670 1661 1.11 1.12 1.01
Graph 1 Structural Wt. comparison for frames subjected to UDL
CONCLUSION
 Vertical bracing members of either 'chevron' type (Frame A-2) or 'knee brace' type
(Frame A-3) provides support to beams in resisting vertical loads. Hence, by adding
bracing members, vertical deflection and thereby size of the beams can be reduced.
 Because of nature of moment frame higher weight (section sizes) are required while as
for remaining two frame because of presence of bracing lower section sizes are
required.
 Combined frame or partial braced frame are economical than moment frame.
 Fabrication and erection cost may get higher in Combined frame and partial braced
frame as compared to moment frame.
 The use of combined frame/ Partial braced frame blocks the passage for access and
piping.
1856
1670 1661
1000
1100
1200
1300
1400
1500
1600
1700
1800
1900
A-1 A-2 A-3
STRUCTURALWT.(kg)
STRUCTURE

4.1.2 UDL and Point load comparison for moment frame
A-1 A-2 A-3 A-4
Fig. 17 Moment Frames with UDL & Point Load
Fig. 17 shows four moment frames having similar geometry with different types of
vertical loading. However, total vertical loads remain same in all four frames. In Frame
A-1 vertical load is applied in the form of UDL at each level. In frame A-2 same UDL as in
frame A-1 is applied in the form of point load at midspan of the beam. In frame A-3, two
point loads are applied at each level. One at 1/3rd length of the beam while other at 2/3rd
length of the beam respectively. In frame A-4, single point load at 1/3rd span of the beam
is applied at each level. Vertical deflection, strength ratio and structural weight are
compared to study the effect of uniformly distributed load and point load on the
structural frame. In frame A-1, UDL on the first tier is 6.0 kN/m2 and on the second and
third tier is 3.0 kN/m2 which is applied as 36 kN/m on the first tier and 18 kN/m on
Moment frame
with UDL
Moment frame
with Point load
at mid span
Moment frame
with Point load at
1/3rd & 2/3rd span
Moment frame
with Point load
at 1/3rd span

second and third tier considering transverse frames are spaced at 6.0 m c/c. On frame
A-2, point load equivalent to UDL in frame A-1 is applied at the centre of the beam. On
frame A-3, two point load each having half the magnitude that in frame A-2 is applied at
1/3rd and 2/3rd span of the beam. On frame A-4, point load having same magnitude as
that in frame A-2 is applied at 1/3rd span of the beam. Support condition at the base i.e.
at junction of pedestal and base plate is considered as pinned.
a. Effect on Deflection and Strength ratio
For these frames, effect on Strength ratio and deflection has been studied while keeping
same member sizes in each frame. The strength ratio and maximum deflection of the
beam (in mm) in each frame is shown below in line diagram. The deflection values are
indicated by ( )* and strength ratio value by [ ]*. Following points are observed from
Fig. 18:
 Maximum deflection is observed in frame A-2 subjected to point load at centre and
least deflection is observed in frame A-1 subjected to UDL.
Fig. 18 Deflection & Strength ratio comparison

 Strength utilization is maximum in frame A-2 subjected to single point load at centre
and least in frame A-1 subjected to UDL.
b. Effect on Structural weight
Effect on structural weight is studied by satisfying strength and serviceability criteria for
above framing systems. Serviceability is checked for the beam member by restricting the
vertical deflection to span/360, while stress ratio is restricted to 1.0 in order to satisfy
strength criteria for every member in the frame. Results of structural weight comparison
are shown below in Table 2 as well as in graphical form in Graph 2. Here P-1 and P-2 are
applied vertical point load. Following points are observed from Error! Reference
source not found.
 Structural weight requirement is maximum for frame subjected to vertical load in the
form of point load at the midspan i.e. frame A-2 and minimum for frame subjected to
vertical load in the form of UDL i.e. frame A-1.
Table 2 Structural Wt. comparison for frames with UDL & Point load
P-1 (kN) P-2 (kN)
(A-2)/(A-1) (A-3)/(A-1) (A-4)/(A-1)
A-1 A-2 A-3 A-4
108 216 1951 2164 2050 2115 1.11 1.05 1.08

Graph 2 Structural Wt. comparison for frames with UDL & Point load
 Frame A-2 requires about 12% higher steel compared to frame A-1.
CONCLUSION
 Disposition of vertical load affects bending moment and deflection of beams.
 When load is acting as a single concentrated load, its effect on beam deflection and
strength ratio will be higher as its location is closer to mid-point of the beam.
 When load is acting more uniformly distributed way, i.e. more no. of point loads or
UDL (Uniformly Distributed Load), deflection and strength ratio of beam will reduce.
 For small diameter pipe it will be economical to apply load in the form of UDL.
 For large diameter pipe the load can be distributed to UDL for pipe shoe length or
can be applied as point load depending on the decision of structural engineer.
1951
2164
2050
2115
1800
1850
1900
1950
2000
2050
2100
2150
2200
A-1 A-2 A-3 A-4
STRUCTURALWT.(kg)
STRUCTURE

EFFECT OF HORIZONTAL LOAD ON DIFFERENT FRAMING SYSTEM4.2
4.2.1 Braced frame, Moment frame, Combined frame and Partial braced
frame comparison (subjected to horizontal load)
A-1 A-2 A-3 A-4
Braced frame Moment frame Combined frame Partial braced frame
Fig. 19 Framing Systems Subjected to Horizontal Load
Four different framing system, Braced frame (frame A-1), Moment frame (frame A-2),
Combined frame (frame A-3) and Partial braced frame (frame A-4) have been selected
and same horizontal load in the form of point load is applied at beam column junction in
every frame as shown in Fig. 19.
a. Effect on Deflection
Lateral load is applied at each tier level in order to study effect on deflection of each
structural framing system. For comparing the deflection of above framing systems,
section sizes are kept same in every frame except addition of some bracing members.
Strength and serviceability checks are satisfied for minimum value of lateral load i.e.
10kN and then load is increased from 10kN to 40kN at interval of 10kN without

considering strength and serviceability criteria in order to see change in behaviour of
deflection when stiffness of the beams and columns are kept same in each framing
system. Results of lateral deflection at top level are shown below in Table 3 as well as in
graphical form in Graph 3. Following points are observed from Table 3:
 Deflection in moment frame (frame A-2) is maximum and least in braced frame
(frame A-1).
 Deflection in Partial braced frame and combined frame is less than moment frame
but more than braced frame.
Table 3 Deflection comparison for frames subjected to Horizontal load
Graph 3 Deflection comparison for frames subjected to Horizontal load
A-1
A-2
A-3
A-4
0
50
100
150
200
250
0 10 20 30 40 50
STRUCTUREDEFLECTION(mm)
LOAD (kN)
A-1
A-2
A-3
A-4

Effect on structural weight with increase in loading is studied by restricting the sway to
permissible limits i.e. H/200 (H is height of frame) and stress ratio not exceeding 1.0.
Horizontal deflection in each structural framing system is kept same for same value of
loading. Results of structural weight comparison are shown below in Error! Reference
source not found. as well as in graphical form in Graph 4. Here P is applied horizontal
load to the frame. Following points are observed from Table 4:
 Structural weight of moment frame is maximum and braced frame is minimum.
 The structural weight requirement for Partial braced frame and Combined frame is
less than Moment frame but higher than Braced frame.
Table 4 Structural Wt. comparison for frames subjected to Horizontal load
Graph 4 Structural Wt. comparison for frames subjected to Horizontal load
A-1
A-2
A-3
A-4
0
500
1000
1500
2000
2500
3000
3500
4000
4500
0 10 20 30 40 50
STRUCTURALWT.(kg)
LOAD (kN)
A-1
A-2
A-3
A-4

CONCLUSION
 Braced frame (A-1) offers high lateral load resisting capacity. When lateral load value
increases it undergoes less change compared to other type of frames.
 Partial braced frame (A-3) offers better behaviour than Moment frame (A-2). This
framing solution can be adopted for piperack structures, wherever possible. However
connection feasibility need to be checked for Partial braced frame. Partial braced
frame used in minor axis of the column will have significantly reduced stiffness (and
hence effectiveness to resist deflection) as compared to Braced frame.
 If clear space is available provide bracing in major direction as well.
 Bracing in the framing system will increase cost of fabrication and erection.
 Deflection is minimum in Braced frame, which is in line with the assumption made
for the stress analysis of the piping system.
 If possible, providing partial brace or bracing at bottom level to reduce deflection and
tonnage.

4.2.2 Support condition comparison
A-1 A-2
Fixed Base Pinned Base
Fig. 20 Frames with Fixed & Pinned Support Condition
Two frames A-1 and A-2 are with same structural arrangement but with different support
condition at base plate level, i.e. A-1 with fixed base and A-2 with pinned base are
compared for deflection, strength ratio, structural weight, column sizes and support
reaction. Horizontal load P is applied at beam column junction in both the frames as
shown in Fig. 20.
a. Effect on Deflection and Strength ratio
Effect on strength ratio and deflection value is studied for same section size and same
load. Result of horizontal deflection at the top of the frame is shown below in Table 5 as
well as in graphical form in Graph 5. The ratio of actual load to allowable load is known
as strength ratio. The strength ratio of each member is shown below in line diagram in

Graph 5 Deflection comparison for Fixed Fig. 21 Strength ratio comparison
Here P is applied horizontal load to the frame.
Table 5 Deflection comparison for Fixed & Pinned base frame
P (kN)
STRUCTURE DEFLECTION (mm)
(A-2) / (A-1)
A-1 A-2
30 30.3 77.8 2.57
Graph 5 Deflection comparison for Fixed Fig. 21 Strength ratio comparison
& Pinned base frame
b. Effect on Structural weight and Column size
Effect on structural weight is studied by applying same lateral load of 30kN at each tier
level in both the frames. Strength and serviceability criteria are satisfied for both the
frames. Horizontal deflection in both the frames is kept same and within permissible
limits i.e. H/200 (H is height of frame) and stress ratio is restricted to 1.0. Column sizes
are also compared for this value of structural weight. Column sizes are compared to
know which frame offers higher useable space. Smaller the section size higher is the
useable space. Results of structural weight comparison are shown below in Table 6 as
30.3
77.8
0
20
40
60
80
100
A-1 A-2
STRUCTUREDEFLECTION
(mm)
STRUCTURE

well as in graphical form in Graph 6. Column sizes for both the frames are shown in line
diagram in Graph 6 Structural Wt. comparison for Fixed Fig. 22 Column size
comparison Here P is applied horizontal load to the frame.
Table 6 Structural Wt. comparison for Fixed & Pinned base frame
P (kN)
(A-2) / (A-1)
A-1 A-2
30 3068 3642 1.19
Graph 6 Structural Wt. comparison for Fixed Fig. 22 Column size comparison
& Pinned base frame
c. Effect on Reactions
Effect on reaction by changing base condition is studied here. Support reaction of both
the frames for same loading on both the frames is tabulated below. Here P is applied
horizontal load to the frame.
3068
3642
2600
2800
3000
3200
3400
3600
3800
A-1 A-2
STRUCTURALWT.(kg)
STRUCTURE

Fig. 23 Support Reaction
Table 7 Reaction comparison for Fixed & Pinned base frame
P (kN)
Base Fixed Base Pinned
HA VA MA HB VB MB HA VA MA HB VB MB
30 44.9 -68.8 153.3 45.1 68.8 153.9 45 -120 0 45 120 0
CONCLUSION
 Column base type effects bending moment and lateral deflections of the columns. i.e.
with fixed type of base conditions, deflection and column size (thereby structural
weight) is lower than that of pinned base frame for same set of loadings.
 The nature and magnitude of loads transferred to foundation changes with base
connection type. Fixed type of base transfers moments and lower tension force to
foundation. This will directly effect design of base plate and foundation, which has to
be investigated while selection of base condition.
 Based on above, for fixed type of base condition the foundation will be bigger than
pinned type base condition. For pinned type of base condition sizes / weight of
structural member will be higher than fixed type base condition.

 Deflection of the frame is less for fixed type base condition, which is favourable
condition for piping system.
 For fixed base condition, anchoring system will be higher so that pedestal size will
increase and because of that space requirement will be higher.
 Foundation sizes for fixed base will be higher compared to pinned base which may
create interface issue with underground utilities.

4.2.3 Effect of frame Height to Width ratio
A-1 A-2
2 tier – 9.0m wide frame 3 tier – 6.0m wide frame
Fig. 24 Frames with Same Useable Space
Two frames with same structural framing system have been selected and horizontal load
P is applied at beam column junction. Total horizontal load applied on both the frames is
same (i.e. horizontal load is equally distributed at each tier level). Load on frame A-1 is
45 kN at each tier and on fame A-2 is 30 kN at each tier. As shown in Fig. 24, height and
width of frame A-1 is 8.0 m and 9.0 m respectively. Height and width of frame A-2 is
11.0 m and 6.0 m respectively. Hence height to width ratio for frame A-1 is 0.89 while
that for frame A-2 is 1.83.
In order to study effect on deflection, of height to width ratio of frames, weight of both
the structural frames is kept same. Permissible deflection for frame A-1 is 40 mm and for

frame A-2 is 55 mm. As both the frames having total horizontal load P and having
different height, to make the results of deflection comparable, ratio of actual deflection to
the permissible deflection of the top node for respective frame is compared. Results of
deflection comparison are shown below in Table 8 as well as in graphical form in
Graph 7.
Table 8 Deflection comparison for frames with same useable space
P (kN)
Actual Deflection / Permissible Deflection
(%) (A-2)/(A-1)
A-1 A-2
90 82.64 88.33 1.07
Graph 7 Deflection comparison for frames with same useable space
Effect on structural weight is studied by restricting the sway to permissible limits i.e.
H/200 (H is height of frame) and stress ratio not exceeding 1.0. Strength and
serviceability criteria are satisfied for both the frames. Lateral deflection is the governing
criteria for design in both the frames A-1 and A-2, hence while comparing the structural
weight, ratio of actual deflection to the permissible deflection is kept same. Results of
82.64
88.33
60
70
80
90
A-1 A-2
ACTUAL/PERMISSIBLE
DEFLECTION(%)
STRUCTURE

structural weight comparison are shown below in Table 9 as well as in graphical form in
Graph 8. Here P is total applied horizontal load to the frame.
Table 9 Structural Wt. comparison for frames with same useable space
P (kN)
(A-2)/(A-1)
A-1 A-2
90 3829 3901 1.02
Graph 8 Structural Wt. comparison for frames with same useable space
CONCLUSION
 Broader the base of the structure i.e. lower height/ width ratio higher the stiffness of
the frame against lateral loads. Higher height / width ratio of frame results in higher
deflection and tonnage.
 Lower height / width ratio will occupy higher space in the plant while higher height /
width ratio will have more number of connections compared to frame with lower
height / width ratio.
3829
3901
3500
3600
3700
3800
3900
4000
A-1 A-2
STRUCTURALWT.(kg)
STRUCTURE

4.2.4 Effect of Elevation of Load point
20 kN @ each tier 30 kN @ 1st tier 30 kN @ 2nd tier 30 kN @ 3rd tier
A-1 A-2 A-3 A-4
Fig. 25 Frames with Change in Elevation of Load Point
In frame A-1, 20 kN load is applied at each tier of frame. Now load is increased at
different level. The effect of this change in magnitude of the load is studied on deflection
and structural weight. In frame A-2, point load is increased to 30 kN at first tier level
while keeping other point load same. In the same way, point load is increased to 30 kN at
second and third tier level in frame A-3 and A-4 respectively while loads at other level
are kept 20 kN. Same is shown in Fig. 25.
In order to study effect on deflection with change in height of load point on frames,
section sizes are kept constant for all the frames i.e. A-1, A-2, A-3 and A-4. Lateral
deflection at top node of the frame is measured. Results of deflection comparison are

shown below in Table 10 as well as in graphical form in Graph 9 It is observed from
Table 10 that frame A-1 has least deflection and frame A-4 has maximum deflection.
Table 10 Deflection comparison for change in elevation of load point
(A-2) / (A-1) (A-3) / (A-1) (A-4) / (A-1)
A-1 A-2 A-3 A-4
53.8 57.8 62.1 68.4 1.07 1.15 1.27
Graph 9 Deflection comparison for change in elevation of load point
Effect on structural weight with change in height of load point on frames is studied by
restricting the sway to permissible limits i.e. H/200 (H is height of frame) and stress
ratio not exceeding 1.0. Hence strength and serviceability criteria are satisfied in each
case. Also utilization in each case is restricted to same value so that structural weight of
frames A-1, A-2, A-3 and A-4 can be made comparable. Results of structural weight
comparison are shown below in Table 11 as well as in graphical form in Graph 10. It is
observed from Table 11, that frame A-1 has least structural weight and frame A-4 has
maximum structural weight.
53.8
57.8
62.1
68.4
0
10
20
30
40
50
60
70
80
A-1 A-2 A-3 A-4
STRUCTURE

Table 11 Structural Wt. comparison for change in elevation of load point
(A-2) / (A-1) (A-3) / (A-1) (A-4) / (A-1)
A-1 A-2 A-3 A-4
3052 3131 3223 3320 1.03 1.06 1.09
Graph 10 Structural Wt. comparison for change in elevation of load point
CONCLUSION
 As the point of application of lateral loads moves away from base (higher elevation
from ground), its effect on structural frame increases due to higher lever arm.
 The same incremental load occurring at higher elevation results significantly higher
effect on structural behaviour. If load is to be increased than, to minimize its effect on
steel structure, it should be preferred to do so at lower level of the structure.
3052
3131
3223
3320
2900
3000
3100
3200
3300
3400
A-1 A-2 A-3 A-4
STRUCTURALWT.(kg)
STRUCTURE

4.2.5 Single bay moment frame and Multiple bay frame comparison
A-1 A-2 A-3 A-4
Fig. 26 Single Bay & Multiple Bay Moment Frame
This exercise is done to understand the behaviour and cost effectiveness of multiple bay
frame with different structural arrangement compared to single bay frame. Useable
space in single bay frame and multiple bay frames is kept same. Different multiple bay
frames are compared with single bay moment frame. Frame A-1 is single bay moment
frame and all the connections in frame A-1 are rigid connection. Frame A-2 is multiple
bay frame having two bays. One bay in frame A-2 has shear connection while other bay
has rigid connection. Frame A-3 is multiple bay combined frame in which bracing is
provided at lower level in one of the bay. Shear connection are provided at lower level
and in the bay with bracing in frame A-3 while all other connections are rigid connection.
Frame A-4 is multiple bay frame with two bays having all rigid connections. Same is
shown in Fig. 26.
Single bay
Moment frame
Multiple bay
frame with 1-bay
Moment
connection
Multiple bay
Combined frame
Multiple bay
Moment frame

Each of the structural framing system shown above is applied same lateral load to study
effect on deflection. Structural weight for every framing system is kept same while
comparing deflection. Results of deflection comparison are shown below in Table 12 as
well as in graphical form in Graph 11. Here P is applied horizontal load to the frame.
Following points can be observed from Table 12:
 It is observed that frame A-3 i.e. Multiple bay combined frame has minimum
deflection of 31.3 mm while frame A-2 i.e. Multiple bay frame with 1-bay moment
frame has maximum deflection of 79 mm.
 Single bay moment frame i.e. frame A-1 has about 86% more deflection compared to
Multiple bay combined frame i.e. frame A-3.
Table 12 Deflection comparison for Single bay & Multiple bay frame
P (kN)
(A-2)/(A-1) (A-1)/(A-3) (A-1)/(A-4)
A-1 A-2 A-3 A-4
30 58.3 79.0 31.3 45.3 1.36 1.86 1.29
Graph 11 Deflection comparison for Single bay & Multiple bay frame
58.3
79.0
31.3
45.3
0
10
20
30
40
50
60
70
80
90
A-1 A-2 A-3 A-4
STRUCTURE

Structural weight of different multiple bay frames and single bay frame is compared by
keeping the utilization same in every frame. Strength and serviceability criteria are
satisfied for each frame. Lateral deflection is restricted to permissible limits i.e. H/200
(H is height of frame). Stress ratio is restricted to 1.0, so that strength criteria are
satisfied. Results of structural weight comparison are shown below in Table 13 as well as
in graphical form in Graph 12. Here P is applied horizontal load. Following points can be
observed from Table 13:
 It is observed that structural weight of multiple bay combined framed is least and
multiple bay frame with 1 bay moment connection is maximum.
 Structural weight of single bay moment frame is about 33% more compared to
multiple bay combined frame.
Table 13 Structural Wt. comparison for Single bay & Multiple bay frame
P (kN)
(A-2)/(A-1) (A-1)/(A-3) (A-1)/(A-4)
A-1 A-2 A-3 A-4
30 4570 5021 3447 4388 1.10 1.33 1.04
Graph 12 Structural Wt. comparison for Single bay & Multiple bay frame
4570
5021
3447
4388
0
1500
3000
4500
6000
A-1 A-2 A-3 A-4
STRUCTURALWEIGHT(kg)
STRUCTURE

CONCLUSION
 Additional column requires additional foundation, hence in assessment of cost
effectiveness; cost of the superstructure and substructure should also be taken in to
account. Additional column in the frame also helps in lateral load resistance of the
frame.
 From serviceability and strength point of view, Multiple bay combined frame
(frame A-3) is most economical.

4.2.6 Composite frame and Steel frame comparison (subjected to horizontal
load)
A-1 A-2
Fig. 27 Composite Frame & Steel Frame
As shown in Fig. 27, two frames dimensionally similar but frame A-1 having RCC column
of 3.5 m in the lower part while frame A-2 made completely from steel is subjected to
horizontal point load at beam column junction. The size of RCC column in frame A-1 is
800 x 600 mm and connection at the junction of RCC and steel column is taken as
pinned connection.
Beam and column steel sections used in both the frames are same while comparing
deflection of both the frames. Results of deflection comparison are shown below in
Table 14 as well as in graphical form in Graph 13. Here P is applied horizontal load to the
Concrete - Steel
Composite frame
Steel frame

frame. It is observed from Table 14, that frame A-1 has less deflection compared to frame
A-2.
Table 14 Deflection comparison for Composite & Steel frame
P (kN)
(A-2) / (A-1)
A-1 A-2
30 31.2 51.8 1.66
Graph 13 Deflection comparison for Composite & Steel frame
Effect on structural weight is studied by applying same loading on both the frame at
same load point and satisfying design requirements. Lateral deflection is restricted to
permissible limits i.e. H/200 (H is height of frame). Stress ratio is restricted to 1.0 so
that strength criteria are satisfied. Utilization of both the frames is kept same and within
permissible limit while comparing the structural weight. Results of structural weight
comparison are shown below in Table 15 as well as in graphical form in Graph 14. It is
observed from Table 15, that structural steel requirement for frame A-1 is less compared
to frame A-2.
31.2
51.8
0
10
20
30
40
50
60
A-1 A-2
STRUCTUREDEFLECTION
(mm)
STRUCTURE

Table 15 Structural Wt. comparison for Composite & Steel frame
P (kN)
(A-2) / (A-1)
A-1 A-2*
30 1720 2624 1.53
* Weight of A-2 frame is considered above 3.5 m.
Graph 14 Structural Wt. comparison for Composite & Steel frame
CONCLUSION
 Concrete columns offer higher resistance to lateral loads due to higher stiffness.
Hence Composite frame results in to lesser deflection and lesser structural steel (with
additional concrete).
 Due to higher size of concrete column compared to steel section, useable space will be
reduced comparatively while anchoring requirement will be less in concrete - steel
composite frame (frame A-1) compared to steel frame (frame A-2).
1720
2624
0
500
1000
1500
2000
2500
3000
A-1 A-2*
STRUCTURALWEIGHT(kg)
STRUCTURE

4.2.7 Plan bracing system
Plan view 3D view
Fig. 28 Frame with No Plan Bracing
Fig. 28 shows Plan view and 3D view of frame with no plan bracing. Error! Reference
source not found. shows the position of vertical bracing. In middle frame vertical
bracing is absent. The arrangement of the vertical bracings remain same for all four cases
shown in the following sections. All the Beam – column connection in X – direction are
shear connection while that in Y – direction are rigid connection.
a. Effect on horizontal drift
Fig. 29 shows plan view of different structural systems. There is no plan bracing in frame
A-1 while in frame A-2, A-3 and A-4 different types of plan bracing is present. The load
P-1, P-2 and P-3 are horizontal load applied at top level of the frame and beam – column
junction in all the frames at top level has been numbered as shown in Fig. 29.

A-1 A-2
No Plan Bracing Plan Bracing (X Type)
A-3 A-4
Plan Bracing (Girder Type) Plan Bracing (Diamond Type)
Fig. 29 Different Plan Bracing System
In this case comparison of horizontal deflection is done for different load cases and
results are shown in Table 16 to Table 19. Also comparison of horizontal drift is done to
check which plan bracing give better diaphragm effect. The ratio of maximum horizontal

deflection to the minimum horizontal deflection at top level of the frame is termed as
horizontal drift. Result of horizontal drift at top of the frame is shown below in
Error! Reference source not found. as well as graphical form in Graph 15. The
sample calculation of horizontal drift for case 1 of frame A-1 is shown below.
Horizontal drift = 23.9/0.7 = 35.8
Table 16 Deflection comparison for frame without plan bracing
Frame
A-1
LOAD (kN)
HORIZONTAL DEFLECTION
(mm)
P-1 P-2 P-3 NODE 1 NODE 2 NODE 3
CASE 1 25 25 25 0.7 23.9 0.7
CASE 2 25 50 25 0.9 29.1 0.9
CASE 3 50 25 25 1.1 24.2 0.7
Table 17 Deflection comparison for frame with X-type plan bracing
Frame
A-2
LOAD (kN)
(mm)
CASE 1 25 25 25 0.7 0.8 0.7
CASE 2 25 50 25 0.9 1.0 0.9
CASE 3 50 25 25 1.1 1.0 0.7
Table 18 Deflection comparison for frame with Girder type plan bracing
Frame
A-3
LOAD (kN)
(mm)
CASE 1 25 25 25 0.7 2.8 0.7
CASE 2 25 50 25 0.9 4.7 0.9
CASE 3 50 25 25 1.1 3.0 0.7
Table 19 Deflection comparison for frame with Diamond type plan bracing
Frame
A-4
LOAD (kN)
(mm)
CASE 1 25 25 25 0.7 1.0 0.7
CASE 2 25 50 25 0.9 1.5 0.9
CASE 3 50 25 25 1.1 1.2 0.7

Table 20 Horizontal Drift ratio comparison for frames with or without Plan brace
LOAD (kN) DRIFT RATIO
P-1 P-2 P-3 A-1 A-2 A-3 A-4
CASE 1 25 25 25 35.8 1.1 4.0 1.5
CASE 2 25 50 25 32.4 1.1 5.0 1.7
CASE 3 50 25 25 36.2 1.6 4.3 1.8
Graph 15 Drift ratio comparison for frames with or without Plan brace
b. Effect on structural weight
Fig. 30 shows plan view of different structural systems. Frame A-1 has no plan bracing
and has only grating beams. Frame A-2 has X type plan bracing arrangement. Frame A-3
has plan bracing in the form of girder of 1.5m width. It also has tie beam connected to
grating beam, which helps in reducing effective length (ly) of grating beams i.e. beam
parallel to Y- axis. Frame A-4 has diamond type bracing arrangement. All the frames are
subjected to horizontal load P at beam – column junction at the floor level. In addition to
that, frames are also subjected to vertical load of 10 kN/m2. Effect on structural weight is
studied by restricting the sway to permissible limits i.e. H/200 (H is height of frame) and
strength ratio not exceeding 1.0.
0
5
10
15
20
25
30
35
40
A-1 A-2 A3 A4
DRIFTRATIO
STRUCTURE
CASE 1
CASE 2
CASE 3

A-1 A-2
No Plan Bracing Plan Bracing (X Type)
A-3 A-4
Plan Bracing (Girder Type) Plan Bracing (Diamond Type)
Fig. 30 Plan View of Frames for Structural Wt. Comparison
Results of structural weight comparison (floor weight only) are shown below in
Table 21 as well as in graphical form in Graph 16.
Table 21 Structural Wt. comparison for frames with & without Plan bracing
P (kN)
STRUCTURAL WEIGHT* (kg)
(A-2)/(A-1) (A-2)/(A-3) (A-2)/(A-4)
A-1 A-2 A-3 A-4
25 6652 6796 5150 4673 1.02 1.32 1.45
* Floor weight only.

Graph 16 Structural Wt. comparison for frames with & without Plan bracing
CONCLUSION
 Absence of plan bracing induces high torsion in the structure. Due to plan bracing
floor works as rigid diaphragm and because of that deflection shared by each column.
 System A-2, shows uniform distribution of horizontal deflection as compared to
system A-3.
6652 6796
5150
4673
0
1500
3000
4500
6000
7500
A-1 A-2 A-3 A-4
STRUCTURALWT.(kg)
STRUCTURE

4.2.8 Vertical bracing in frame
In this case effect of change in location of vertical bracing has been studied. In frame A-1,
vertical bracings are placed in one bay and from frame A-2 to A-5 bracings are placed in
different bays. Same is shown in below figures.
A-1
A-2

A-3
A-4
A-5

a. Effect on support reactions
Effect on support reactions is studied, when position of bracing is changed from one bay
to other in the frame. Here P is applied horizontal load at first and second level of the
frame and 2P is the applied horizontal load on third and fourth level of the frame.
Support reaction of all the frames for same loading on all the frames is tabulated in
Table 22 for positive direction of forces and in Table 23 for negative direction of forces.
Below shown line diagram of frame explains direction of support reaction FX and FY.
Fig. 31 Sign Convention for Support Reaction

Table 22 Support reaction comparison for (+ ve) forces
P (kN) FRAME
SUPPORT REACTION (kN)
NODE 1 NODE 2 NODE 3 NODE 4 NODE 5 NODE 6
FX1 FY1 FX2 FY2 FX3 FY3 FX4 FY4 FX5 FY5 FX6 FY6
30
A- 1 0.0 0.0 0.0 0.0 -30.0 -105 -30.0 105 0.0 0.0 0.0 0.0
A- 2 0.0 0.0 0.0 0.0 -30.0 -75.0 -30.0 45.0 0.0 30.0 0.0 0.0
A- 3 0.0 0.0 0.0 0.0 -30.0 -75.0 -30.0 55.4 0.0 9.3 0.0 10.3
A- 4 0.0 0.0 0.0 0.0 -30.0 -49.2 -30.0 23.5 0.0 -4.2 0.0 29.9
A- 5 0.0 0.0 -30.0 -49.0 -30.0 24.0 0.0 6.0 0.0 9.0 0.0 10.0
Table 23 Support reaction comparison for (- ve) forces
P (kN) FRAME
SUPPORT REACTION (kN)
NODE 1 NODE 2 NODE 3 NODE 4 NODE 5 NODE 6
FX1 FY1 FX2 FY2 FX3 FY3 FX4 FY4 FX5 FY5 FX6 FY6
30
A- 1 0.0 0.0 0.0 0.0 30.0 105 30.0 -105 0.0 0.0 0.0 0.0
A- 2 0.0 0.0 0.0 0.0 30.0 75.0 30.0 -45.0 0.0 -30.0 0.0 0.0
A- 3 0.0 0.0 0.0 0.0 30.0 75.0 30.0 -55.4 0.0 -9.3 0.0 -10.3
A- 4 0.0 0.0 0.0 0.0 30.0 49.2 30.0 -23.5 0.0 4.2 0.0 -29.9
A- 5 0.0 0.0 30.0 49.0 30.0 -24.0 0.0 -6.0 0.0 -9.0 0.0 -10.0
CONCLUSION
 When vertical bracings are kept in one bay only throughout the height of the frame
than load is distributed only in two columns.
 When vertical bracings are arranged in multiple bays, each column will share push
pull where vertical bracings are placed.
 Foundation become lighter when vertical bracings are scattered.
 More number of foundations affected when loads increased, at latter stage of project,
in case of scattered vertical bracing.

Effect of Substructure modelling on Superstructure Page 65
INTRODUCTION TO PART II
GENERAL5.1
In conventional analysis of any civil engineering structure the super structure is usually
analysed by treating it as independent from foundation and soil medium on the
assumption that no interaction takes place. This usually means that by providing fixity at
the support structural analyst simplifies soil behaviour, while geotechnical engineer
neglects structural behaviour by considering only the foundation while designing.
When a structure is built on soil some of the elements of the structure are in direct
contact with the soil. When the loads are applied on the structure, internal forces are
developed in both the structure and as well as in soil. This results in deformations of
both the components (structure and soil) which need to be compatible at the interface as
they cannot be independent of each other. Because of this mutual dependence, which is
termed as interaction, the stress resultants in structure and, stresses and strains in soil
are significantly altered during the course of loading. Therefore it becomes imperative to
consider the structure-foundation and soil as components of a single system for analysis
and design of the structure and its foundation. The analysis that treats structure
foundation - soil as a single system is called as Soil Structure Interaction (SSI)
analysis.
The effect of soil immediately beneath and around the structure, on the response of the
structure when subjected to external loads is considered in soil structure interaction. In
CHAPTER 5

Parametric study of various structural framing systems & effect of substructure modelling on super structure

Parametric study of various structural framing systems & effect of substructure modelling on super structure

Recommended

Recommended

More Related Content

Similar to Parametric study of various structural framing systems & effect of substructure modelling on super structure

Similar to Parametric study of various structural framing systems & effect of substructure modelling on super structure (20)

Recently uploaded

Recently uploaded (20)

Parametric study of various structural framing systems & effect of substructure modelling on super structure